Project Summary The Gram negative pathogen, Aggregatibacter actinomycetemcomitans, is the etiologic agent of localized aggressive periodontitis (LAP) and other systemic infections, including infective endocarditis. Like other pathogenic Gram negative organisms, A. actinomycetemcomitans produces outer membrane vesicles (OMVs), which encapsulate virulence factors for delivery to target cells. A. actinomycetemcomitans OMVs are enriched in a leukotoxin (LtxA), and strains that produce more LtxA also secrete more OMVs, indicating that LtxA may play a role in the delivery of the OMVs to the host cell. The specific role of LtxA in this process has not yet been fully demonstrated. To accomplish this, the PI intends to systematically study the lipid and protein components of both the OMV and the target cell required for delivery of the OMV to the target cell. The research will answer vital questions about the pathogenicity of A. actinomycetemcomitans, and result in the identification of specific factors that could be targeted for the treatment of infection. In our future work, we will develop molecules to target these factors for the development of antibiotic alternative treatments. In addition, we will investigate the delivery of OMVs to other bacterial cells, to understand their role in cell-to-cell communication.